1. Field of the Invention
The present invention is directed to a method and apparatus for growing poultry in an indoor environment. In particular, it is directed to an apparatus for efficiently heating and ventilating a poultry house and a method for using the same.
2. Description of the Prior Art
In the poultry industry, as well as other industries where domesticated fowl are cared for in an indoor environment, the temperature and ventilation of the environment must be carefully managed. However, proper heating of the indoor environment may complicate the problems associated with its ventilation. Similarly, proper ventilation may induce improper heating. Therefore, it is necessary to strike a proper balance between the two.
Currently, the poultry industry utilizes a specified arrangement of brooder heaters, exhaust fans and curtains to facilitate the proper heating and ventilation of a poultry house. The brooder heaters are special heating units which provide the necessary heat for the poultry house and are sized according to the number of chickens the house can hold. At a minimum, one 30-40,000 BTU brooder heater should be utilized for every 750 chickens. These brooder heaters can be staggered down the center of the poultry house or, alternatively, staggered from side to side throughout the house. The brooder heaters use fully-on or fully-off type burners.
The exhaust fans of a typical poultry house are placed along the length of one of the poultry house walls. In most houses, the exhaust fans are mounted along the north wall. Due to the rigorous ventilation requirements, the exhaust fans employ 36" diameter blades.
The curtains of a typical poultry house are disposed along one side of the house opposite the exhaust fans as well as between the exhaust fans. Together, the curtains and exhaust fans provide the necessary cross-flow ventilation. At a minimum, four fans must be used with separate timers and overrides in houses greater than 350' in length. To provide the necessary ventilation while attempting to maintain heating efficiency, the exhaust fans are operated in a cyclic fashion. In most houses, the exhaust fans are on for a period of two minutes followed by an eight minute off period.
Many poultry houses are provided with a brooding section which is partitioned off from the rest of the house. Due to the added ventilation requirement of the chicks in such a brooding section, two fans are located therein.
Baby chicks, in particular, are extremely sensitive to temperature changes that occur within the poultry house. Any temperature changes prove to be extremely critical during the first three weeks of the six-week grow-out period (the time it takes for the baby chicken to grow to a sufficient size for processing). During the grow-out period, a 10.degree. F. temperature deviation can stunt the growth of the chick and cause the chick to experience poor feed conversion (the ratio between the amount of food used to feed a chicken per pound of weight for the full grown chicken). Such a temperature deviation is often experienced by the chicks when they wander away from the brooders. Therefore, it is imperative to maintain the temperature throughout the poultry house at a constant level for the duration of the grow-out period.
There are certain known temperatures at which the chick will experience optimal growth and feed conversion. Specifically, during the first three weeks of the grow-out period, the poultry house, or brooding section thereof, should be maintained at a temperature that is no less 85.degree. F. During the second three weeks of the grow-out period, this temperature level should be maintained at no less than 72.degree. F.
Ventilation of the poultry house serves three main purposes. First, proper ventilation removes moisture from the house. Second, proper ventilation removes poisonous gases, such as ammonia and carbon dioxide, from the poultry house. The ammonia is generated by the baby chicks when their feces are mixed with the moisture laden make-up air and wood chips or rice hulls on the house floor. In an average poultry house, 300 pounds of chick manure is produced per 24 hour period thereby causing a high humidity environment which perpetuates the harmful effects of the ammonia gases and further promotes the growth of bacteria and fungi. Carbon dioxide is present in the poultry house as a result of normal respiration. Third, proper ventilation provides fresh breathable air for the chickens. Overall, the air in the poultry house must be exchanged at least four times per hour to supply the baby chicks with enough breathable fresh air to survive.
Feed expenses account for 60% of the cost of producing chickens. Therefore, a proper starting point for optimizing the chicken production process should focus on the feed and its associated variables (i.e., weight of the chickens and the feed conversion).
The proper heating and ventilation of the poultry house can have a significant effect on the weight and feed conversion of the chicken and, as a result, on the feed costs. When the temperature is too cold, the feed is consumed and converted to body heat rather than tissue for growth. The maximum feed conversion during the six week grow-out period is achieved at the 85.degree. F. and 72.degree. F. temperatures noted above. Thus, it must be recognized that there is a delicate balance which must occur between eliminating the moisture and gases from the poultry house, while at the same time providing the proper ventilation and warmth for the baby chickens.
As noted, the heating and ventilation of the poultry house influences the weight and feed conversion of the chickens. For instance, where the chickens are of good weight but experience poor feed conversion, the house is likely too cool thereby wasting feed from the feeders. Where the chickens are light in weight but are experiencing a good feed conversion, the house is likely too warm and the chicks are not receiving sufficient feed or water. If the chickens are light in weight and are further experiencing poor feed conversion, the poultry house ventilation is likely inadequate thereby causing a build up of ammonia.
The focus of the policies with respect to the heating and ventilation management of poultry houses has heretofore been primarily concerned with lowering fuel bills. This perspective loses site of the most important factor of the grow-out period---- chick comfort. By being overly concerned with energy savings, the chicks are exposed to an unstable environment of sudden temperature changes and improper ventilation thereby causing illness, and even death, among the chicks.
During cold weather operation, growers are often instructed to keep the curtains closed so that fresh air may be pulled through the cracks and crevices of the house when the exhaust fans turn on. This policy of keeping the curtains closed, in con]unction with the cyclic operation of the exhaust fans, causes two primary problems. First, cold air from the outside is immediately directed through the curtains to the floor when the exhaust fans turn on. Since the temperature of the poultry house is typically warmer than the cold outside air, the baby chicks experience a shock due to the sudden change in temperature. As a result of the influx of cold air, the brooder heaters turn on to elevate the poultry house to the proper temperature. However, at the same time that the brooder heaters are increasing the poultry house temperature, the ammonia and carbon dioxide gas as well as the humidity inside the house are also increasing.
Second, the cyclic exhaust fan operation and the closed curtains cause the poultry house to assume a negative air pressure with respect to the outdoor pressure. Consequently, there is an improper air flow which is generated throughout the house. Additionally, the cyclic operation of the exhaust fans submit the baby chicks to periods of stagnant, ammonia laden, high humidity conditions approximately 80% of the time.
Thus, it will be recognized that the poultry house environment is in a continuous cycle of change. When the poultry house temperature drops, the brooder heaters turn on. When the brooder heaters turn on, the humidity, ammonia, and carbon dioxide concentration levels increase. When those levels increase in this stagnant air condition, the exhaust fans turn on for 2 minutes and then off for 8 minutes. Nothing in the poultry house environment remains constant. The chickens are either too cold or too warm and they are either breathing fresh air for 2 minutes, or hot stagnant air for 8 minutes. This ever-changing environment brings illness and death to chickens throughout the entire poultry house.